High-pressure sealing assembly

ABSTRACT

A high-pressure sealing arrangement is provided for sealing a gap ( 26 ) between two concentric machine parts ( 4, 5 ) which can be moved relative to each other, of which a first machine part ( 4 ) comprises a groove ( 3 ) and a second machine part ( 5 ) comprises an outer peripheral surface ( 7 ) opposite the groove ( 3 ). A sealing ring ( 1 ) of an extrusion-resistant material and a tensioning ring ( 2 ) of an elastomeric material are provided in the groove ( 3 ). A shaped section of the sealing ring ( 1 ) on the low-pressure side can be deflected towards the outer peripheral surface ( 7 ) under fluid pressure load. When the pressure decreases, the pressure-dependent deflection of the sealing ring ( 1 ) automatically returns towards the initial, unpressurized state of the sealing ring ( 1 ). The sealing ring ( 1 ), viewed in cross-section and in the unpressurized state, has a shaped sealing ring surface ( 6 ) facing the outer peripheral surface ( 7 ), which merges at least with respect to the shaped section on the low-pressure side, into a shoulder surface ( 13 ) separated from the outer peripheral surface ( 7 ) at a first separation d 1 , which merges into a shoulder surface ( 13 ) side surface ( 20 ) with a second, larger separation d 2  from the outer peripheral surface ( 7 ).

The invention relates to a high-pressure sealing arrangement for sealingthe gap between two concentric machine parts which can be moved relativeto each other, of which a first machine part comprises a groove and thesecond machine part comprises an outer peripheral surface opposite tothe groove.

PRIOR ART

A high-pressure sealing arrangement of this type is disclosed e.g. in DE43 23 266 A1.

In the conventional arrangement for sealing the gap between twoconcentric machine parts which can be moved relative to each other, thegroove has a sealing ring which is stationarily mounted in the machineelement. The sealing ring is flexible with respect to radial and axialforces acting on the sealing ring. The pressure-dependent deformation ofthe sealing ring is reversible, i.e. when the fluid pressure on thehigh-pressure side drops, the sealing ring automatically assumes itsinitial shape. The sealing surface or sealing edge can bepressure-relieved.

OBJECT OF THE INVENTION

It is the underlying purpose of the invention to further develop theconventional sealing arrangement to further improve the frictional andextrusion behavior in the region of dynamic sealing.

SUBJECT MATTER AND ADVANTAGES OF THE INVENTION

This object is achieved with a high-pressure sealing arrangement,wherein the groove has a sealing ring of an extrusion-resistant materialand a tensioning ring of an elastomeric material, wherein, under fluidload, a shaped section of the sealing ring on the low-pressure side canbe deflected towards the outer peripheral surface, wherein thepressure-dependent deflection of the sealing ring automatically returnstowards the initial unpressurized state of the sealing ring when thepressure is reduced, wherein the sealing ring, viewed in cross-sectionand in the unpressurized state, has a shaped sealing ring surface facingthe outer peripheral surface, which merges, at least with respect to theshaped region on the low-pressure side, into a shoulder surface which isseparated from the outer peripheral surface at a first separation d₁,which merges into a shoulder surface side surface with a larger, secondseparation d₂, from the outer peripheral surface.

The shape of the sealing ring surface may be indented, wavy or stepped.The sealing ring surface has a support foot or a support section withthe pre-tensioned sealing surface. This provides sealing at low fluidpressures. At higher pressure loads, the support foot or support sectiontilts and the sealing surface is pressure-relieved, an edge, step orprojection having an edged or round shape on the shoulder surface on thelow-pressure side, is placed thereon and becomes a sealing edge orsealing surface. In this fashion, the pressure relief of the sealingring elements abutting the outer peripheral surface of the secondmachine part is improved. The sealing ring is produced from a materialwhich is harder than that of the tensioning ring and has a highermodulus of elasticity. The core of the invention is the selection of thematerials and of the multi-stage sealing ring surface in the region ofthe outer peripheral surface of the second machine part. Thismulti-stage sealing ring surface may be placed on the outer peripheralsurface after pivoting of the sealing ring. Friction produced byrotation and translation of the second machine part is reduced.

The sealing ring is preferably symmetrical. When the pressure isreduced, the pressure-dependent deflection of the sealing ringautomatically returns towards the initial state of the sealing ring inthe unpressurized state, wherein the sealing ring—viewed incross-section and in the unpressurized state—has a shaped sealing ringsurface which faces the outer peripheral surface and merges on bothsides in steps into two shoulder surfaces which are separated from theouter peripheral surface and merge into side surfaces via at least oneedge.

In a further development of the invention, the shoulder surfaces mergeinto the side surfaces via inclined surfaces which extend transverselyto the outer peripheral surface. One gap each is formed towards thehigh-pressure side and towards the low-pressure side. Fluid may getbelow the inclined surface on the high-pressure side when pressure isexerted which supports pivoting of the sealing ring.

The inventive high-pressure sealing arrangement can be used for rotarytransmission in hydraulics.

DRAWING

The schematic drawing shows one embodiment of the inventive sealingarrangement which is explained in the following description. The objectsshown in the individual figures and sections of the sealing arrangementare partially greatly enlarged and the distortion is exaggerated to showthe function of the sealing arrangement more clearly.

FIG. 1 shows a cross-section of a sealing arrangement without or withlittle pressure load;

FIG. 2 shows the sealing arrangement of FIG. 1 under high pressure load.

DESCRIPTION OF THE EMBODIMENT

FIG. 1 shows a sealing ring 1 made from an extrusion-resistant rigidmaterial such as polyurethane or similar materials, and a tensioningring 2 from an elastomeric material. The sealing ring 1 and thetensioning ring 2 are installed in a groove 3 of a first machine part 4which is disposed opposite to a rotatable second machine part 5. Thesealing ring 1 and the tensioning ring 2 together are larger than thegroove 3. Through introduction of the sealing ring 1 and tensioning ring2 into the groove 3, a sealing surface 6 of a support foot or supportsection is pressed to an outer peripheral surface 7 of the secondmachine part 5 to permit reduction of the interference in the staticsealing region. In the installed state, shown in FIG. 1, the tensioningring 2 is pre-tensioned on the groove bottom 8 and abuts the groovebottom 8 and a groove flank 11 on the low-pressure side through contactlines 9 and 10. The contact lines 9 and 10 have the function ofstatically active sealing edges.

In FIG. 1, H designates the high-pressure side and N designates thelow-pressure side. In FIG. 1, the sealing ring is loaded with a lowfluid pressure. The sealing ring 1 has a substantially trapezoidalcross-sectional shape, wherein the sealing ring side facing the outerperipheral surface 7 has several shapes. A central sealing surface 6associated with a dynamic sealing region merges on both sides in stepsinto two shoulder surfaces 13 and 14 which are separated from the outerperipheral surface 7 to form spaces 15 and 16. The shoulder surfaces 13and 14 are each connected to side surfaces 19 and 20 of the sealing ringvia inclined surfaces 17 and 18 which extend transversely to the outerperipheral surface 7. The inclined surfaces 17 and 18 intersect the sidesurfaces 19 and 20 at edges 21 and 22. The shoulder surfaces 13 and 14intersect the inclined surfaces 17 and 18 at edges 23 and 24. The rearside 25 of the sealing ring 1 abuts the tensioning ring 2. The sealingring 1 seals a gap 26 between the machine parts 4 and 5. Relevant forthe invention are two different separations d₁ and d₂, wherein thelatter is not constant in the present case due to the inclined surface.If formed like a step, d₂ would e.g. also be constant.

FIG. 2 shows the sealing ring 1 which is pressurized from thehigh-pressure side H. The sealing ring 1 is loaded in the direction ofarrow 27 with pressure P. The sealing ring 1 is pressed to the grooveflank 11 via the fluid pressure P. Due to the shape of the sealing ring1, the sealing ring 1 is pivoted towards the low-pressure side N suchthat the edge 23 is pressed to the outer peripheral surface 7. The edge23, the shoulder surface 13 and the central sealing surface 6 form aclosed annular space 28. The edge 23 and the partially pressure-relievedsealing surface 6 assume the function of a dynamic sealing. The sealingring 1 abuts the outer peripheral surface 7 flatly via the sealingsurface 6 and linearly via the edge 23. The sealing ring 1 and thetensioning ring 2 are compressed on the groove flank 11 on thelow-pressure side and abut planarly. The inclined surface 18 is liftedby the fluid pressure P. The rear side 25 is curved towards thetensioning ring 2. The distance between shoulder surface 14 and outerperipheral surface 7 increases. The fluid can penetrate under theshoulder surface 14.

The deformation on the groove flank 11 and the pressure onto or theseparation from the outer peripheral surface 7 differ in dependence onthe strength of the pressure load (fluid pressure P).

This deformation is reversible and decreases with decreasing pressure.

LIST OF REFERENCE NUMERALS

-   1 sealing ring-   2 tensioning ring-   3 groove-   4 machine part-   5 machine part-   6 sealing surface-   7 outer peripheral surface-   8 groove bottom-   9 contact line-   10 contact line-   11 groove flank-   13 shoulder surface-   14 shoulder surface-   15 space-   16 space-   17 inclined surface-   18 inclined surface-   19 side surface-   20 side surface-   21 line of intersection-   22 line of intersection-   23 edge-   24 edge-   25 rear side-   26 gap-   27 direction of arrow-   28 annular space-   d₁ separation from the outer peripheral surface-   d₂ separation from the outer peripheral surface

1. A sealing arrangement comprising: a first machine part (4) having agroove (3); a second machine part (5) having an outer peripheral surface(7) opposite the groove (3) and spaced apart from the first machine part(4) by a gap (26); a sealing ring (1) disposed in the groove adjacentthe peripheral surface (7), the sealing ring (1) including a shapedsection having a central sealing surface (6) parallel to the outerperipheral surface (7), the central sealing surface (6) merging on bothsides in steps into two shoulder surfaces (13, 14), the shouldersurfaces (13, 14) intersecting inclined surfaces (17, 18) at edges (23,24), both edges being in a spaced apart relationship with the outerperipheral surface (7) and both shoulder surfaces (13, 14) beingparallel to the outer peripheral surface (7) the shoulder surfaces (13,14) each being connected to side surfaces (19, 20) of the sealing ring(1) via the inclined surfaces (17, 18) which extend transversely to theouter peripheral surface (7), whereby the inclined surfaces (17, 18)intersect the side surfaces (19, 20) at further edges (21, 22); whereinthe sealing ring (1) has a substantially trapezoidal cross-sectionalshape, wherein the rear side (25) of the sealing ring (1) is parallel tothe outer peripheral surface (7), and sealing ring side surfaces (19,20) are disposed at an angle to groove flanks (11); the anglerelationship of the side surfaces (19, 20) to the groove flank (11)enabling pivoting of the sealing ring (1) about the central sealingsurface (6) thereby enabling sealing contact being the edge (23) and theperipheral surface (7) with an annular space (28) between the sealingcontact and the central sealing surface (6) and simultaneous fullcontact between the side surfaces (19, 20) and the groove flanks (11),the annulus space (28) defining spaced apart seals between the sealingring and the peripheral surface (7); and a tensioning ring (2) disposedin the groove (3) against a rear side (25) of the sealing ring (1).